NZXT H3 Flow - Traditional mATX tower layout with NZXT's clean aesthetics. Also NZXT's crap included fixed speed case fans. Throw some Thermalright TL-C12 fans in there if you have some hotter equipment.

Lian Li A3-mATX - One of the smallest mATX cases you can get that supports 360 AIOs and very long GPUs. With the caveat that you have to take care that your PSU isn't too big if you have a GPU longer than 330mm. If your GPU is less than 330mm long, you can fit a 200mm PSU. If it's longer than 330mm, you'll want a PSU that's 150mm or preferably 140mm long, or an SFX PSU. And if you want both a long GPU and a 360 AIO, you'll need an SFX PSU. Also works fine with many dual tower air coolers too, so you don't need an AIO.

Jonsbo D31/D32/Z20 - Jonsbo makes a ton of mATX cases. These three are basically even more compact implementations of the layout the A3-mATX uses. The Z20 in particular is smaller than many ITX cases, but that one does require an SFX PSU. Where as the D31 and D32 work with ATX PSUs, with the same caveats as the A3-mATX in that it's highly dependent on the size of the PSU and length of the GPU. But instead of 330mm being the cutoff, it's \~288mm for the max GPU length for PSUs longer than 150mm. It too can take tower coolers, though not as tall, and its limited to 240 AIOs.

Phanteks XT M3/V3 - This one looks like it's maybe similar to an A3-mATX, just with glass side and front (for the V3 version), but it's quite a bit bigger. Though it is still reasonably compact for an mATX case apart from being fairly long. Big benefit of these two is they come with a ton of good fans, and you don't need to worry about the GPU or AIO colliding with the PSU depending on the size, so you can use any components you want!*

* As long as said PSU is 150mm or smaller as that's all the case can handle!

Unlike the Lian Li and Jonsbo cases I mentioned, the case itself has a hard limit on the PSU size.

...

On the cases the other two people mentioned:

Lian Li Vector V100R Mini - this is a massive case when it comes to mATX dwarfing most traditional ATX towers out there today. But it's inexpensive, comes with 4 good fans, and has a look many people like. For $65 its hard to beat if you're looking for that open wrap around front glass look.

Fractal Define 7 Mini - The Define series of cases are ones I used for nearly a decade. But they're an old design at this point. Closed front restricts airflow, and the max GPU length is realistically 300mm. It claims 330mm, but you have to remove the front fans. Most likely if your GPU can fit in this case, it'll fit in the Jonsbo D32 Mesh with a long PSU. To be fair, the Jonsbo cases are all bottom intake designs, so their airflow is seemingly just as restricted, but if you go with the mesh side panel versions they'll pull a lot of air through the side panels instead. It's also about the same size as the H3 Flow, which has better component compatibility across the board.

The one thing the Define cases have over basically everyone else... 4 USB-A and a USB-C on the top. Which is really nice.